A typical airbag assembly comprises an inflatable airbag held in an enclosure having on a cover on a side turned toward the person being protected. This cover in turn has a door or flap that is joined on one edge at a hinge to the rest of the cover but that is connected at its other, usually three, edges to the rest of the cover via weakened tearaway or break lines typically formed by a row of perforations.
In a collision, the airbag is inflated and pushes out the cover, breaking it free along the three break lines and pivoting it at the hinge so the bag can open and deploy in front of its enclosure. The hinge is provided to anchor the flap and prevent it from being propelled outward and potentially injuring the person in front of the airbag assembly.
This secure hold of the flap in the region of the hinge is achieved by additional non-breaking threads in the hinge region, as it is known from U.S. Pat. No. 8,348,303. These known airbag covers are expensive to manufacture.